Densities, Ultrasonic Velocities, Excess Properties and IR Spectra of Binary Liquid Mixtures of Organic Esters (Ethyl Lactate, Some Organic Carbonates)

Organic esters of carbonic acid {dimethyl carbonate (DMC)/diethyl carbonate (DEC)/propylene carbonate (PC)}, in combination with a lactate ester {ethyl lactate (EL)}, with green chemistry characteristics were chosen for the present study of molecular interactions in binary liquid mixtures. Densities ( ρ ) and ultrasonic velocities ( U ) of the pure solvents and liquid mixtures were measured experimentally over the entire composition range at temperatures (303.15, 308.15, 313.15 and 318.15) K and atmospheric pressure. The experimental data was used to calculate thermodynamic and acoustic parameters V m E , κ S E , L f E , V ¯ m,1 , V ¯ m,2 , V ¯ m,1 E , V ¯ m,2 E , V ¯ 1 E,0 and V ¯ 2 E,0 and the excess functions were fitted with the Redlich–Kister polynomial equation to obtain the binary solution coefficients and the standard deviations. It was observed that the values of V m E , κ S E and L f E are positive for the mixtures of (EL + DMC/DEC) and negative for those of (EL + PC) over the entire range of composition and temperature. The positive values of V m E , κ S E and L f E indicate the action of dispersion forces between the component molecules of (EL + DMC/DEC) mixtures whereas negative values for the mixture (EL + PC) suggest the existence of strong specific interactions between the component molecules, probably resulting from chemical and structural contributions. The excess properties have also been analyzed by using the reduced ( Y E / x 1 x 2 ) excess function approach and the results are found to be in agreement with those from the corresponding Y E (= V m E , κ S E and L f E ) values. This is further supported by FTIR spectral analysis.